This invention relates to the consumption of energy generated or supplied by a utility; and more particularly, to controlling the amount of consumption in response to increased load demands on the utility at peak times of usage, as well as in response to occurrences at the utility affecting its ability to supply energy.
Electrical energy is a form of energy that can be traded as a commodity, but cannot be stored. Rather, it must be generated as it is used. The traditional approach used by electrical utilities to manage energy is referred to as “reliability based”. Using this approach, the utility brings additional generation capability on-line, in order to meet increased loads placed on the utility's power distribution system. Under this process, the system's operator must be careful to match the amount of electricity generated to the amount of load on the system. When, however, a crisis develops and the load threatens to exceed the supply, the utility will attempt to take action in order to maintain a stable system. At such times, account representatives at the utility may call upon certain, large electricity consumers (customers) and ask them if they would temporarily go off-line. If, however, the utility owns a load-control system (such as the TWACS® Load Control system), the utility can directly issue load-shed commands to thousands (or even millions) of electricity consuming devices located throughout the distribution network, and get them to go partially (or completely) off-line. This approach works solely on the basis of system reliability, without much concern for the supply-side economics that accompany the crisis situation.
A newer approach to managing energy in some areas is “price-based”. This approach allows market forces to affect the price of electricity, and allows the consumer to buy (or not buy) electricity in response to changes in its price. When a power generation shortfalls occur, the scarcity of the commodity makes it more valuable, and the price for electricity, in a free-market economy, should rise. Conversely, when a surplus of electrical generation occurs, the price of electricity should fall. A free market economy automatically allows generators with low operating costs to obtain the lion's-share of the sale of electricity, with the consumer benefiting from its lower price. As the price rises, however, generators with more expensive operating costs are able to profitably contribute to the grid, and stability is maintained. Real Time Pricing (RTP), in all of its many forms, requires constant communication among all of the stakeholders. In a “pure”, de-regulated RTP environment, the wholesale price of electricity rises and falls on the spot-market as a function of supply; and, depending on whatever contracts are in place, will likely be immediately reflected in the retail-price of energy. These retail prices can be communicated to consumers using a communication system such as TWACS®. Prices might be rendered in terms of cents per kWh (or dollars per MWh); but, alternatively, can be rendered in terms of a tiered pricing scheme. As set out hereinafter, such a scheme might use names such as “normal”, “elevated”, “Critical Peak 1”, “Critical Peak 2”; or a color code scheme such as “green”, “yellow”, “orange”, “red”. Regardless of the labels used, all such schemes require communication with the consumers and/or their equipment in near real-time.
Many utilities currently employ a two-way automatic communication system such as TWACS® by which the utility sends messages to, and acquires information from, its customers. Communications with TWACS® provides the utility with “fresh” load information on the system. Historical usage information can be used to create distribution system models, with recent, fresh information used to verify the accuracy of the models. The models are then used to predict when peak demands on the system can be expected to occur for different times of the year, as well as for various sets of circumstances such as temperature and time of day.
However, in addition to the demands placed upon a distribution system during the normal course of events and which a utility can to some degree predict, other circumstances may occur which are not planned, yet which have an immediate impact on the supply of electricity to consumers. A generator 10 (see FIGS. 1 and 3) might suddenly drop off-line, a ground-fault may occur, an unexpected load will draw substantial amounts of power. Any of these can escalate to a point where the system becomes unstable. When such an occurrence happens, it can be readily ascertained in a number of ways. For example, one measure of the severity of the problems is that when too much load is placed on the system, generators start to run marginally slower. This is evidenced by a drop in the frequency of the electricity generated. In such instances, things can start to quickly unravel. While new communication technology can enable price-based, demand response programs such as described above to work in these situations, there still exists a need for an autonomous, emergency over-ride capability.